Green tea, made from the leaves of Camellia sinensis plant, has been consumed for centuries in Asian countries. In recent years, the popularity of green tea has increased globally due to its numerous health benefits.

One of the most significant benefits of green tea is its potential to reduce the risk of cardiovascular disease (CVD), a leading cause of death worldwide. In this article, we will explore the evidence supporting the use of green tea to decrease cardiovascular mortality.

The link between green tea and cardiovascular health

The potential health benefits of green tea are attributed to its high content of polyphenols, particularly flavonoids.

Flavonoids possess antioxidant and anti-inflammatory properties, which can help to improve the function of blood vessels, reduce blood pressure, and prevent the formation of blood clots that can lead to heart attacks and strokes. Studies have shown that green tea consumption is associated with a reduced risk of CVD and its risk factors, such as hypertension, hyperlipidemia, and diabetes.

Green tea and hypertension

Hypertension, or high blood pressure, is a major risk factor for CVD. Epidemiological studies have shown that regular green tea consumption is associated with lower blood pressure levels.

A meta-analysis of 25 randomized controlled trials, involving 1,476 participants, found that green tea consumption significantly reduced both systolic and diastolic blood pressure compared to control groups. The effect was most prominent in individuals with hypertension. The anti-hypertensive effect of green tea is thought to be due to its ability to increase the production of nitric oxide, a molecule that relaxes blood vessels and improves blood flow.

Green tea and hyperlipidemia

Hyperlipidemia, or high levels of blood lipids, is another major risk factor for CVD.

Studies have shown that green tea catechins, particularly epigallocatechin gallate (EGCG), can reduce the levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides in the blood, while increasing the levels of high-density lipoprotein (HDL) cholesterol. A meta-analysis of 14 randomized controlled trials, involving 1,136 participants, found that green tea catechin consumption significantly reduced the levels of total and LDL cholesterol compared to control groups.

The lipid-lowering effect of green tea is thought to be due to its ability to inhibit the absorption of dietary fat in the intestine and to increase the excretion of cholesterol in the bile.

Green tea and diabetes

Diabetes, a chronic metabolic disorder characterized by high blood sugar levels, is a major risk factor for CVD. Epidemiological studies have shown that green tea consumption is associated with a reduced risk of type 2 diabetes.

A meta-analysis of 17 prospective cohort studies, involving 543,225 participants, found that green tea consumption was associated with a 18% reduced risk of developing type 2 diabetes. The anti-diabetic effect of green tea is thought to be due to its ability to improve insulin sensitivity, reduce insulin resistance, and reduce inflammation.

Green tea and cardiovascular mortality

The evidence supporting the use of green tea to decrease cardiovascular mortality is primarily based on observational studies, which have shown an inverse association between green tea consumption and the risk of CVD mortality.

A meta-analysis of 13 cohort studies, involving 487,314 participants, found that green tea consumption was associated with a 20% reduced risk of CVD mortality. The protective effect of green tea was observed in both men and women, and in both Asian and Western populations.

Green tea and other cardiovascular risk factors

In addition to hypertension, hyperlipidemia, and diabetes, green tea consumption may also help to reduce other cardiovascular risk factors, such as obesity, inflammation, and oxidative stress.

A meta-analysis of 11 randomized controlled trials, involving 821 participants, found that green tea catechin consumption significantly reduced body weight, body mass index, and waist circumference compared to control groups. The anti-inflammatory and antioxidant properties of green tea may also help to reduce the risk of atherosclerosis, a chronic inflammatory process that can lead to heart attacks and strokes.

Conclusion

The evidence supporting the use of green tea to decrease cardiovascular mortality is promising, but further research is needed to establish the optimal dose, duration, and frequency of green tea consumption for maximum cardiovascular benefit.

Green tea consumption should not be considered as a substitute for a healthy lifestyle and appropriate medical treatment of cardiovascular risk factors. Nevertheless, incorporating green tea into a heart-healthy diet and lifestyle may provide additional cardiovascular protection.